以中间相沥青基炭纤维和中间相沥青为主要原料,并添加一定量多壁碳纳米管,通过热压成型和高温热处理工艺制备一维高导热C/C复合材料.采用偏光显微镜、扫描电镜、激光热导仪、电子万能试验机等对复合材料的微观结构、导热性能和力学性能进行表征.结果表明,碳纳米管的添加导致复合材料的孔隙率下降和体积密度升高,而且对复合材料的力学性能及不同方向的导热性能都有显著影响.随着碳纳米管添加量的增加,复合材料沿炭纤维轴向的室温热扩散系数逐渐降低,而垂直于纤维轴向的抗弯强度和室温热扩散系数均呈现先上升后下降的趋势.经过2900℃石墨化处理后,添加体积分数3%碳纳米管的复合材料垂直于纤维轴向的抗弯强度为113.4 MPa、热扩散系数为40.1 mm2/s,较未掺杂碳纳米管时分别提高了56%和79%.%With mesophase pitch-based carbon fiber and mesophase pitch added by a certain amount of multi-walled carbon nanotubes (CNTs)as the main materials,one dimensional (1D)carbon/carbon (C/C)composites with high thermal conductivity were prepared by hot-pressing and high temperature treatment.Microstructure,thermal conductivity and mechanical properties of the composites were characterized by polarized light microscope (PLM),scanning electron microscope (SEM),laser ther-mal conductance instrument and electronic universal testing machine.The results show that the addi-tion of CNTs reduces the porosity and raises the bulk density of the composites,and it also has signif-icant effects on their mechanical properties and thermal conductivities in different directions.With the increase of CNTs content,the composites'thermal diffusivity at room temperature along carbon fi-ber's axial direction declines gradually,but the flexural strength and thermal diffusivity perpendicular to the axial direction first increase then decrease.For the composite with 3 vol.% CNTs graphitized at 2900 ℃,the flexural strength and thermal diffusivity perpendicular to fiber's axial direction reach 113.4 MPa and 40.1 mm2/s,respectively,which are 56% and 79% higher than those of the compos-ite without CNTs.
展开▼
